Hi,
My opinion, still is, that "progressive" is a result of everything else that was happening in the arts and in the social environs. You can look at the 60's and you can see the movie business take off, then you can see theater doing some imaginable things, which had started in the 50's and continued into the 70's and then you can look at art/painting, and it also exploded with the multi media abilities that became better known and more popular. Literature was also not asleep during that time, and many books were very famous in the late 60's during the time that it is given (more or less) as the beginning of "progressive music".
Writing a paper on that will be difficult, since many of the scenes were also tied to the arts and not many as many folks are capable of mixing and matching things. The Canterbury scene, is a perfect example, of a scene that took its inspiration from a literary perspective, and all you have to listen to is Robert Wyatt's last album, and find that the free form style that was originally created then, in several different "styles" of music, is still alive and well, and while you and I can sit here and go ...what the heck ... in the end, making the connections is really hard. It makes more sense to even say that Robert Wyatt did his 1, 2 and 3 to make fun of jazz and the upper class folks walking around thinking they were better than the rock folks. One of the best examples of the lack of fear to go out on a limb and be totally free form, but still have the ability to make it work within the context of what they were doing, albeit, I think that this was not as accidental as we think. I really believe that it was quite intentional however, not well defined musically. This is the case in a lot of progressive bands all the way through the rest of the century, as a lot of their material also feels like filler on an album, and not necessarily "progressive" in any way, shape or form.
You, probably, have to make a decision, as to the value of some specific scenes, since "progressive" is way too generic, and while California was more influenced by Kesey and Kerouac in the early days, London was much more literary than that, and in many ways way more classically minded, in the sense that the work had "form", which some of the early California stuff did not!
At this point you will also come across Paris, Munich/Berlin and Tokyo, all three of which were (and still are) massively involved in their own artistic scenes and work. The Germans, even ended up creating a whole literary scene, to go along with the theater and film, which went along with the progressive scene that is known as "krautrock".
All in all, to discuss the scene generically, will make it harder all around to create something more complete that will help you learn about the music and its designs, and ideas, that folks went on with.
I suppose that one could also define the ideas with a music staff and its definitions, although for my tastes taking the music that clinically, takes out the emotion involved. As an example, the idea of the "ragas" is for the musician to get past the mechanics of the music, and take it into a personal level that is "beyond music", and its definition. Jazz, also can do this, but in America, tends to be too formulaic and tied to the notes themselves, as folks consider themselves better musicians than rock folks, which is, of course, highly unfair, as there are just as many folks that well defined and versed in rock music!
I would not write a paper on "progressive music".
For a little "guidance", or probably a suggestion as to how the California scene grew up, take a look at the film "The Trip" about Ken Kesey. There is a line towards the end, that will say it all about the scene and it has to do with people getting into the trip and what it means to them. It is a very important part of it all, in the end, as "drugs" tend to be mentioned as important to all the music in those days, although I seriously believe that those words were more media fear deliverance, than otherwise.
Also remember at the time, that one jerk was going around saying "the medium is the message", which is a serious issue, because it is another social design to make sure you follow the society instead of being different, which normally is not accepted. The medium is NOT the message, or your soul is worthless and stupid! But you have to make up your mind and see that.
Also see the "krautrock" special from the BBC, specially the first 2 segments, because the words in there from Edgar Froese and others are very telling as to what that scene meant, and in general, what the whole "progressive" scene was all about.